W2 Introduction to APT

8/11/2019 W2 Introduction to APT

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Workshop

Introduction to Accelerated

Pavement Testing

Angel Mateos Transport Research Center of CEDEX

3rd International Conference on

Accelerated Pavement Testing

Nick Coetzee Dynatest Consulting, Inc.

What is APT ?

ALT ~ Accelerated Load Testing (of pavements)

APT ~ Accelerated Pavement Testing

Controlled application of a prototype wheel loading, at or above theappropriate legal load limit to a prototype or actual, layered, structural

pavement system to determine pavement response and performanceunder a controlled, accelerated, accumulation of damage in acompressed time period.

(NCHRP Synthesis 235, 1996)

Controlled application of wheel loading to pavement structures for thepurpose of simulating the effects of long-term in-service loadingconditions in a compressed time period.

(NCHRP Synthesis 325, 2004)


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Controlled application

Prototype wheel loading

Prototype or actual pavement

Accelerated accumulation of damage

What is APT ?

Why use APT?


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Why use APT?

Improved understanding of pavement behaviour

Rapid evaluation of pavement performance- months instead of years -

Ability to control variables- load related, pavement related, some environmental -

Ability to evaluate contribution of specific variables topavement performance

- load related, pavement related, some environmental -

No risk to traffic by failure of in-service pavement testsection

Types of APT Facilities


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Types of APT Facilities

Linear Test Tracks

Circular Test Tracks

ROLLING WHEELS

PULSE LOADING DEVICES

TEST ROADS

Fixed Mobile

Real Traffic

Controlled Loading

Types of APT Facilities Linear Test Tracks

Test Section

Rail Beam

Loading

Device

Testing Length

Useful Testing Length

at Constant Speed

Mobile


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Types of APT Facilities Circular Test Tracks

Central

Pivot

Movement

Direction

Test

Sections

Cart

LoadingDevice

1

2

34

5

6 High Speed

Simultaneous

Testing

Types of APT Facilities Pulse Loading Devices

Test Section

Loading

Device

Load Frame


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Types of APT Facilities Test Roads

Mn-ROAD

main line

low-volume loop

Mn/ROAD Truck

(manually driven)

Highway

-94

(Real Traffic)

Types of APT Facilities European Full-Scale Facilities


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Types of APT Facilities USA Full-Scale Facilities


Real traffic (not APT)

MnROAD Va Smart Road

LTPP

Controlled loading

NCAT (drivers) WesTrack (driverless) MnROAD LVR Older road tests (AASHO, WAASHO)

Full-Scale Road Tests


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MnROAD


Va. Smart Road


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Asphalt PlantLaboratory

North

Lee County Road

1.7 Mile Oval Test Track on 309 acres

46 Cooperatively Sponsored 200 ft Test Sections

4700 sq ft Onsite Testing Laboratory

2600 sq ft Onsite Truck Maintenance Facility

NCAT


VEHICLE LOADING

Trucks Currently Run 18 Hours a Day

Truck ESALs Logged Continuously via VIS, MileageLog, & Tube

No Trucking Monday for Data Collection & VehicleMaintenance


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WesTrack


FAA (NAPTF)

INDOT/Ohio

Kansas

Linear APT facilities - fixed


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FAA

NAPTF


INDOT/Purdue


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Ohio DOT


Kansas


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Linear APT facilities - mobile

ALF

FHWA

LTRC

ATLaS

University of Illinois

HVS Mk III/IV

Caltrans FDOT USACOE CRREL

HVS Mk V

USACOE WES

MLS

TxDOT

Other


ALF - FHWA


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ATLaS


HVS Mk III


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HVS Mk IV


HVS Mk V


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HVS Mk V


TxMLS


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Types of APT Facilities African and South American Full-Scale Facilities

Types of APT Facilities Oceania Full-Scale Facilities


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Types of APT Facilities Asian Facilities

TRB Committee

AFD40

Full-Scale and Accelerated Pavement Testing

COST 347Improvements in Pavement Research with

Accelerated Load Testing

www.pave-test.com

CAPTConsortium of Accelerated Pavement Testers

HVSIAHeavy Vehicle Simulator International Alliance

The implication of an experienced

country or institution makes sense

APT Network

www.hvsia.co.za


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Applications of APT Testing

Applications of APT Testing

Models calibration

Verification of sections

Comparison of different Pavements

Alternative Designs

New Materials

New Sections

Study of Specific Issues

Rehabilitation Designs and Strategies


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Limitations of APT Testing


Compressed time period of APT test tends to excludeenvironmental effects seen by in-service pavements

Specially built test sections may not be representativeof typical in-service construction

Relatively high cost


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single

materials

under

controlled

conditions

Laboratory

Testing

APT

Testing

Performance

Evaluation

of Real Roads

complete

pavements

under

controlled

conditions

complete

pavements

under

real conditions


BENEFIT

LOW

MEDIU

M

HIGH

Computer Simulation /

Engineering Judgement

FieldT

esting

LaboratoryTestin

g

Long Term Pavement

Performance Studies

Accelerated Pavement

Testing

COST

LOW MEDIUM HIGH


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Real Sections


Controlled Conditions:

Traffic

Environment

Construction

Accelerated Conditions:

Acceleration of

Ageing is difficult

Random combinationof factors

Increased loads

Increased repetitions

Imposed climaticconditions

Reduced scale

pavements Air temperature

Pavement Temperature

Freezing-thaw cycles

Water table level

Rainfa ll

Sun irradiation

Required

extrapolation

APT

Feasibilities of APT Testing


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Feasibilities of APT Testing Traffic Simulation

Load level

Wheel type (single or dual)

Tire type

Tire inflation pressure

Transverse position

Axle typeSpeed

................................... ok

........ ok

..................................... ok

................. ok

................... ok

..................................... ?.......................................... ?


0

20

40

60

80

100

120

140

1

time

AxleLoad(kN)

APT Traffic Real Traffic

Random Distribution of

Real Traffic is Difficul t to

Reproduce


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Vehicle 1

Vehicle 2

Track 1 Track 2 Track 3 Track 4 Track 5 Track 6 Track 7

Track 1 Track 2 Track 3 Track 4 Track 5 Track 6 Track 7

60 mm 60 mm 60 mm 60 mm 60 mm 60 mm

60 mm 60 mm 60 mm 60 mm 60 mm 60 mm

28

3134

39

4041

37

28

3134

39

4041

37 500

passes

1290 mm

360 mm

CEDEXTest Track


Axle Type can be

Reproduced in Only a Few

Test Tracks

Kansas State Univ.

LCPC

ALF


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12

22 25

60

20

12

20

100

40

0

20

40

60

80

100

120

LAVOC MLS-Swiss RTM CEDEX LINTRACK HVS-Nordic TRL LCPC LIRA

Speed(km/h)

Linear Test Track Circular Test Track

Range of Realistic

Truck Speed

9 Full-Scale European

Test Tracks

Realistic Speed

is Only Reached

in Circular Test

TracksCEDEX can b e

Considered Circular

in this Sense

Air temperature ................................

Air moisture .......

Asphalt temperature ........................

Water table .......

Soils moisture ...

Rainfall .............

Freeze-thaw .....

Feasibilities of APT Testing Environment Simulation

(always) (some facilities)

Controlled

@ Indirect Control

Recorded

(when necessary)


@ (some facilities)(when necessary) (some facilities)


(some facilities)

(always)@ (some facilities)


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air temperature can

be controlled in any

indoor facility

LAVOC

FAA BASt


specially-designed

sheds can be used

for mobile facilities

ATLaS

HVS-Nordic


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a test pit allows

water table control

ATLaS

LCPC

CEDEX

... and homogeneous

support throughout

tests


some facilities are

housed in special

climatic chambers

... where most

environment variables

can be controlled

RTM

LAVOC


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Feasibilities of APT Testing In-Situ Testing

only a few facilities

can be used to test

existing pavements

MLS

HVS

MTS

Testing

RehabilitationStrategies

APT Related Monitoring


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APT Related Monitoring Loading Parameters

Load

Total load Tire pressure/temperature Repetitions

Wheel position (Long. & Transv.)

Wheel speed


HVS Mk IV Load Data - Uni-directional

78.0

78.5

79.0

79.5

80.0

80.5

81.0

0 10 20 30 40 50 60

Time (sec)

Load(kN

)

80 kN Target

HVS Control Data


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Measure the surface contact stresses:

In the vertical plane (Z direction) In the horizontal (X-Y) plane in 2 directions:

Longitudinal stresses Transverse stresses

SIM

APT Related Monitoring Environmental Parameters

Records temperature:

Air Surface In Depth

Moisture in soils

thermocouples

TDR moisture

sensors


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APT Related Monitoring Structural Response

Strain-Gage


LVDT

Sensor


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MBV

V

V

T


MBV

V

V

T

LTVV


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Road Surface

Deflectometer

(RSD)

Surface deflectionsFull deflection bowlsElectronic data processing

0

50

100

150

200

250

300

350

400

450

500

0 50 100 150 200 250

Counts

Deflection(micro

n)

Repeat 1 Repeat 2 Repeat 3


RSD Deflection

Bowls


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JDMD

Measures edge and cornerdeflections (Ideal for PCC testing)


JDMD

Results

-2.0

-1.5

-1.0

-0.5

0.0

0.5

0 1 2 3 4 5 6 7

Distance (m)

Deflectio

n(mm)

Right H side Joint 2 Edge Midspan Left H Side Joint 1

Left H side Joint 2 Right H side Joint 1


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APT Related Monitoring Measuring Performance

Pavement

Deterioration

Asphalt cracking

Permanent deformation

Bearing capacity

Longitudinal unevenness


0

1

2

3

4

5

6

7

8

9

10

11

Number

ofFacilities

Bearing

Capacity

Permanent

Deformation

Surface

Cracking

Longitudinal

Unevenness

Texture Skid

Resistance

Sensors

Response

APT is more related toStructural Performance Less attention to

Surface Quality

Even if

available!

Source:

Survey from 11 Full-Scale European Facili ties (2004)


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0

25

50

75

100

125

0 100 000 200 000 300 000 400 000 500 000 600 000

Number of Cycles

(mm/100)

Section 1 Section 2 Section 3 Section 4 Section 5 Section 6

Water TableLevel Creation

How to separate moisture effect ?


FWD

Test


100%

125%

150%

175%

200%

225%

0 100 000 200 000 300 000 400 000 500 000 600 000

Number of Cycles

Loaded/N

on-Loaded

Section 1 Section 2 Section 3 Section 4 Section 5 Section 6

Cracking

Cracking

Cracking

FWD Test

FWD

Test


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Laser

Profilometer

Measures surface profileContinuous profileElectronic data processing


Rut Profile:

Wandering traffic pattern-5

0

5

10

15

20

0 200 400 600 800 1000 1200 1400

Transverse Distance (mm)

Ru

t(mm

)


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Laser

Profiling


Laser

Profiling


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In-depth deflections andpermanent deformation

Full deflection bowlsElectronic data processing

Multi-Depth

Deflectometer

(MDD)

MDD 12 Permanent Deformation SECTION 409A4 (250 Foamed Bitumen)

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

9.0

10.0

0 50000 100000 150000 200000 250000 300000 350000

REPETITIONS

PermanentDeform

ation(mm)

20mm 275mm 450mm 650mm

PD409. xl s


MDD

Permanent

Deformation


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Benefits

Benefits

Reduction of pavement costs by reducing unnecessarypavement thickness, or by improving the structuralbalance of the design

Avoidance of failure caused by the use of unprovendesigns or by abnormally heavy traffic

Improving pavement design methods including both newand rehabilitation methods

Greater knowledge and understanding of pavement andmaterials behaviour

Rapid evaluation and comparison of rehabilitationmeasures for flexible, semi-flexible (stabilized) and rigidpavements


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Benefits in a nutshell

Better understanding and modelling

minimises underdesign

Better understanding and modelling

minimises overdesign

Allows better (optimal) use of funds and

natural resources

Benefits

Explicit evaluation using B/C ratio not well developed

Australia and RSA estimated B/C ratio of 10 to 12 someyears ago

User cost effects difficult to evaluate

Recent RSA approach using Expected Value (APT08

Tech. Session 7)

Technical benefits typically listed as improved pavementmethods and procedures

Ranges from very general to very explicit

Florida DOT

Sweden

Caltrans

South Africa

Some examples provided by:


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Benefits Florida DOT

FDOT now requires the use of SBS modified binder in ourhigh traffic pavement designs. Benefit is significantperformance improvement.

FDOT now allows the use of fine graded mix designswhere previously course graded mix designs wererequired across the board. Expected benefit is reducedconstruction cost due to reduced compactive effort.Expected performance similar to coarse graded mixes.

Benefits Sweden

In general:

- Increased understanding of pavement behavior- APT08 Tech Session 2

In particular the effect of:

- Different pavement layer materials

- Groundwater level- Temperature in asphalt layers- Thawing- Different pavement strength (relationship between pavement

response and pavement performance)- Compaction of pavement layers- Reinforcement with steel net- Side slope- New designs


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Benefits Caltrans

In general:

- Improved understanding of pavement behavior- M-E pavement design (CalME)- APT08 Keynote session Wednesday; Tech Sessions 1,4,5,6,8,13

In particular:

- Benefit of using tack coat- Benefit of using improved compaction- Confirmed use of thickness RAC- Long life AC pavement design (rich bottom)- FSHCC not critical to PCC rapid reconstruction

- Construction productivity analysis procedure- Dowel bars desirable in JCPCP- Dowel bar retrofit extends service life of JCPCP- ATPB not desirable due to stripping- Reflection cracking model- Modified binder overlay performance

Benefits RSA

In general:

- Very few, if any, aspects of pavement design in RSA notinfluenced by APT

- APT 08 Tech Sessions 1,7

Design, Analysis, Performance:

- RSA pavement structural design (TRH4, SAMDM)- Improved modelling of permanent deformation- Improved modelling of deflection basins

Materials:

- LAMBS- GEMS- Rehabilitation of lightly cemented base pavements- Comparison of labor intensive bases (penetration macadam,

emulsion treated gravel, slurry bound macadam)- Porous asphalt


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Structure of APT Programs

Technology transfer/implementation:

Test level: interaction of champions and steeringcommittee

Test level: broader dissemination through presentations,workshops, site demonstrations

Longer-term: development of generic design parameters,higher degree work

Longer-term: inclusion in national guidelines

Conclusions


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Conclusions

APT is active world-wide

There are different types of ALT facilities

APT limitations APT versus Real Roads

Main studies: structural responsepavement deterioration

APT is a basic tool for any pavement research strategy

International Cooperation on this Area is a Must

- THE END -

Hydraulic Actuator

LINTRACK (Netherlands)

Prototype Wheel Loading

Dead Weight

CEDEX (Spain)

Real Trucks

WesTrack (USA)Pulse Loading

BASt (Germany)


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Prototype or Actual Pavement

Real Pavements

HVS-Nordic (Slovenia)

Outdoors Test Pit

LCPC (France)

Laboratory Facility

OULU (Finland)

Indoors

HVS-Nordic (Sweden)

Accelerated Accumulation of Damage

Increased loads

Increased repetitions

Imposed climatic conditions

Reduced scale pavements

Air temperature

Pavement Temperature

Freezing-thaw cycles

Water table level

Rainfall

Sun irradiation


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CEDEX Test Track

LCPC Test Track

+- 0,5 m

alternative:single axle

tandem axletridemaxle (single wheel)

Test Track

6 m

14,50 m

20,50 m


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LAVOC Test Track

MLS-EMPA-ETH Test Track

Tanks

Linear Motors

Tanks

Linear Motors

10.7m

60kN60kN 3.0mLoading

Wheels

4.2m

65kN65kN3.0m

Electr. Control Gene-rator

DrivingWheels

LoadingWheels

10.7m

60kN60kN 3.0mLoading

Wheels

4.2m

65kN65kN3.0m

Electr. Control Gene-rator

DrivingWheels

LoadingWheels


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BASt Pulse Loading Device

n

nmax.

1 2 3 4 5 6 7

210

180

1,0

0,5

Road Testing Machine


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LINTRACK

LIRA Test Track


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HVS-Nordic

TRL Test Track


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Brazilian Pavement Testing Facility Federal University of Rio Grande do Sul

Brazil Sao Paulo

Other


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South Africa HVS CSIR Built-environment

HVS Mk-IV

Australia ALF ARRB Group Ltd.


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New Zealand test Track CAPTIF

Public Works Research Institute

Test Road

Test Track


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Techno Center of Kajima Road

Nippon Expressway Research Institute


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Southeast University

ChangAn University China

HVS Mk VI


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Chongqing Communications Research

& Design Institute

Tongji University China


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HanYang University

KALES Test Track


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Heavy Vehicle Simulator Mk IV

- India CRRI -

HVS Mk IV

W2 Introduction to APT

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